I just had a great idea.
Because I go through at least 2 pairs of headphones a year, and it adds up, I figured:
1) The expensive part is the speaker driver.
2) cable faults can happen anywhere, but the less cable there is, the less chance of a fault.
So I'm going to take my busted Sennheisers, lop off the cable just below the mic, and then solder on a 3.5mm socket.
Hey-f*cking-presto, I have my decent headphones back, and if there's a cable fault again below the mic, I just have to shell out about a quid for a piece of wire.
Plus, I have a bunch of other busted headphones this will work with. I reckon I just saved myself a bunch of money there.
And for the 3.5mm socket, I've at least got a couple of discmen (bought for lasers, pew pew) laying about I can use, and probably more besides.